Fabrication of Controllable N-Doped Ce_0.2Zr_0.8O₂ via O–N–O Bond with Robust NO Oxidation and Durability at Low Temperature

Abstract

N-doped Ce0.2Zr0.8O2 catalysts for NO oxidation were successfully fabricated via NH3 treatment at high temperature, and the N doping amount could be controlled via adjusting the conditions of various NH3 concentrations and treatment times. The optimal 10N700-5 catalyst revealed the sensational oxidation efficiency at low temperature, which surpassed 50% at 180 °C and reached up to 82.82% at 270 °C. The excellent activity was ascribed to the numerous generations of O2 – and the accompanied vast formation of Cr6+, caused by N doping. N atoms were doped in Ce0.2Zr0.8O2 in the structure of Ce–O–N–O–Zr via the O–N–O bond between N and O. The analysis of affecting factors elucidated that cation ratios played a more significant role than the Brunauer–Emmett–Teller surface area, and Cr6+ ratios acted mostly. Additionally, the conceivable promotion mechanism by N doping for NO oxidation was examined via in situ DRIFTS. This work propelled denitration with the selective catalytic oxidation technique for industrial application and lent a novel perspective for the design of catalysts with satisfied oxidation efficiency at low temperature.

Fabrication of Transition Metal (Mn, Co, Ni, Cu)‐Embedded Faveolate ZnFe2O4 Spinel Structure with Robust CO2 Hydrogenation into Value‐added C2+ Hydrocarbons

“…Type IV isotherms with hysteresis loops of type H3 were observed for all the catalysts, indicating the existence of narrow slit‐like mesopores [20,21] . Combined with the SEM and TEM images, the formation of mesopores was caused by the accumulation of small particles, and a similar phenomenon was observed in our previous work [19] . The SSA values of all catalysts, calculated using the Brunauer‐Emmett‐Teller (BET) model, are listed in Table 1.…”

“…For the ZFO‐containing samples, the first three diffraction rings were assigned to the (1 1 1), (2 2 0), and (3 1 1) crystal planes of ZnFe 2 O 4 . The discontinuous diffraction rings consisting of many diffraction spots were caused by the formation of granulum, [19] as observed in the TEM images. Combined with the HR‐TEM and SAED images, it can be seen that the lattice spacings in CoZFO and NZFO were both smaller than those in pure ZFO, whereas the values remained almost unchanged in CuZFO and MZFO, which was in accordance with the XRD results.…”

“…[20,21] Combined with the SEM and TEM images, the formation of mesopores was caused by the accumulation of small particles, and a similar phenomenon was observed in our previous work. [19] The SSA values of all catalysts, calculated using the Brunauer-Emmett-Teller (BET) model, are listed in Table 1. The results showed that the SSA value of fresh ZFO was higher than that of fresh FO, and introducing transition metals could further increase the value.…”